Japanese Published Unexamined Patent Application No. Hei 9-252277 includes the following description (see FIG. 1): xe2x80x9cInformation transmits by a base station is received by mobile station A, . . . , and after processing is performed by mobile station A, the information is relayed to mobile station B. The information is relayed in turn to mobile stations B, C and D. By relaying information in this manner, only a small amount of electric power is required to transmit information across a wide range.xe2x80x9d In this application, a re-transmission counter value included in a transmission frame is incremented by one each time the information is relayed, and whether an information relay process should be performed is determined in accordance with the re-transmission counter value. The above publication states that by using this method information can be transmitted locally. However, a problem will arise if whether a relay is to be performed is determined in accordance with the number of relays that were performed previously. For example, when mobile wireless stations that are close together relay information to each other, the number of relay operations performed may reach the limit before information has not been delivered to an area far from the base station. In addition, no countermeasures are provided for the congestion that frequently occurs in communications conducted among an increased number of mobile wireless stations.
Furthermore, Japanese Published Unexamined Patent Application No. Hei 10-32538 includes the following description (see FIG. 2): xe2x80x9cWhile running, a mobile object CR1 obtains its current position and the current time from a GPS device GP1. Based on these data, the current running path (route) and the average speed, the time required and the traffic level along the route are obtained and stored as traffic information message MS1 in a memory MM1.xe2x80x9d In addition, the following description is given referring to FIG. 3: xe2x80x9cAssume that mobile objects CR1 and CR2 move toward each until they are at a communicable distance. The mobile object CR2 transmits to the mobile object CR1 traffic information message MS2-2, which is stored in the object CR2. The mobile object CR1 transmits to the mobile object CR2 traffic information message MS1, which is processed by the object CR1, and mail information message MS6, which is addressed to a destination computer. Of the traffic information message MS1 received by the mobile object CR2, the important portion concerning the mobile object CR2 is displayed as the latest arrived information by a display device DS2. Similarly, of the traffic information message MS2-2 received by the mobile object CR1, the important portion concerning the mobile object CR1 is displayed as the latest arrived information by a display device DS1.xe2x80x9d Furthermore, there is the following description in the above application: xe2x80x9cEssentially, the message transmission system in this embodiment does not ensure the arrival of data, and the rate of data arrival must be increased as much as possible . . . . . Actually, since many mobile objects run in the same area, traffic information data for a specific area/route are sequentially updated to the most recently happened data. Particularly in a country like Japan where traffic jams often occur, a mobile object is always present in the vicinity of another mobile object, so that essentially a message can be exchanged at substantially the same high speed and in the same wie range as are those for a wired network.xe2x80x9d Moreover, it is stated in the above application that since an instant message need not be transmitted across a wide range, it is immediately erased instead of being stored for a long time. However, there is no specific explanation concerning a method for determining how instant a message is and for determining the time at which to erase an instant message. In addition, there is no description of the problem that arises when multiple mobile wireless stations are present locally.
In the above conventional art, a mechanism is disclosed for the exchange by mobile wireless stations of information received from a base station. However, it is stated that the processing performed by a mobile station when transmitting information is controlled only by using the number of relays that are affected. It is, therefore, one object of the present invention to provide a method for information transmission control having a more adequate form.
It is one more object of the present invention to avoid congestion of information.
It is another object of the present invention to transmit information more efficiently.
To achieve the above objects, according to the present invention, a wireless transceiver on a reception side performs the steps of: measuring a predetermined property (e.g., a radio strength) of a radio signal received from another wireless transceiver; and by using the measured predetermined property and a corresponding response policy (e.g., a response policy concerning radio strength), determining the response timing to the received radio signal. The predetermined property includes a physical property, and the response policy may be one that is stored internally, or one that is extracted from the received radio signal.
If the measured radio strength satisfies a condition designated by the response policy, the response timing can be set for an earlier time following the receipt of a radio signal than in a case where the condition is not satisfied. When a specific wireless transceiver responds to a radio signal more quickly than does another wireless transceiver, the probability of establishing a connection is increased. Therefore, the probability is increased that a connection will be established between wireless transceivers that matches the response policy.
In particular, if a response policy designates a radio strength equal to or less than a predetermined level and if the measured radio strength is equal to or less than the predetermined level, the response timing can be set for an earlier time following the receipt of a radio signal than in a case where the measured radio strength exceeds the predetermined level. Therefore, the probability will increase that a wireless transceiver which has transmitted a radio signal will be connected with another wireless transceiver at a relatively distant location.
In addition to the above steps, the following steps may be executed: checking the communication history with another wireless transceiver that has transmitted the radio signal; and if the communication history shows that within a predetermined period of time there is a communication with another wireless transceiver, determining that no response to the radio signal will be sent. This occurs because the communication efficiency of the overall system is reduced if, for the exchange of similar information, a specific wireless transceiver is repeatedly connected to the same wireless transceiver within a short period of time.
A wireless transceiver on a transmission side performs the steps of: specifying a response policy concerning a radio strength for other wireless transceivers that will receive a radio signal; and transmitting to other wireless transceivers a radio signal including the specified response policy. As a result, a wireless transceiver on a transmission side can specify a wireless transceiver that is present in an area where the transmitting wireless transceiver desires to establish a connection. That is, in accordance with the response policy a wireless transceiver located at a predetermined distance can be specified.
The response policy can be based either on a radio strength level, or on the range of a radio strength value. In addition, the radio signal which includes the specified response policy can include a terminal mode indicating whether a wireless transceiver on the transmission side only transmits or not. If the wireless transceiver on the transmission side is a base station, it does not need to receive information from a wireless transceiver on the receiving side so long as the terminal mode is included in the radio signal.
The response policy can be changed in accordance with a predetermined condition. If, for example, the wireless transceiver on the transmission side is in an area where a probability is high that multiple other wireless transceivers are located, a low radio strength can be set. But if the wireless receiver on the transmission side is in an area where only a few other wireless transceivers are located, a high radio strength can be set. Further, the radio strength level can repeatedly be switched to low, to high or to intermediate each time a predetermined period has elapsed.
The present invention has been explained as a process performed by a wireless transceiver. But in addition, the present invention can be implemented as a wireless transceiver that has components for performing the individual steps. These steps can be implemented by a program to be executed by a processor included in a wireless transceiver. This program is stored in a storage device, such as a ROM (Read Only Memory). The program may also be stored on a storage medium, such as a hard disk.